/*
 *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "splitting_filter.h"

#include <array>

#include "array_view.h"
#include "channel_buffer.h"
#include "checks.h"

namespace webrtc {
    namespace {

        constexpr size_t kSamplesPerBand = 160;
        constexpr size_t kTwoBandFilterSamplesPerFrame = 320;

    }  // namespace

    SplittingFilter::SplittingFilter(size_t num_channels,
                                     size_t num_bands,
                                     size_t num_frames)
            : num_bands_(num_bands),
              two_bands_states_(num_bands_ == 2 ? num_channels : 0),
              three_band_filter_banks_(num_bands_ == 3 ? num_channels : 0) {
        RTC_CHECK(num_bands_ == 2 || num_bands_ == 3);
    }

    SplittingFilter::~SplittingFilter() = default;

    void SplittingFilter::Analysis(const ChannelBuffer<float> *data,
                                   ChannelBuffer<float> *bands) {
        RTC_DCHECK_EQ(num_bands_, bands->num_bands());
        RTC_DCHECK_EQ(data->num_channels(), bands->num_channels());
        RTC_DCHECK_EQ(data->num_frames(),
                      bands->num_frames_per_band() * bands->num_bands());
        if (bands->num_bands() == 2) {
            TwoBandsAnalysis(data, bands);
        } else if (bands->num_bands() == 3) {
            ThreeBandsAnalysis(data, bands);
        }
    }

    void SplittingFilter::Synthesis(const ChannelBuffer<float> *bands,
                                    ChannelBuffer<float> *data) {
        RTC_DCHECK_EQ(num_bands_, bands->num_bands());
        RTC_DCHECK_EQ(data->num_channels(), bands->num_channels());
        RTC_DCHECK_EQ(data->num_frames(),
                      bands->num_frames_per_band() * bands->num_bands());
        if (bands->num_bands() == 2) {
            TwoBandsSynthesis(bands, data);
        } else if (bands->num_bands() == 3) {
            ThreeBandsSynthesis(bands, data);
        }
    }

    void SplittingFilter::TwoBandsAnalysis(const ChannelBuffer<float> *data,
                                           ChannelBuffer<float> *bands) {
        RTC_DCHECK_EQ(two_bands_states_.size(), data->num_channels());
        RTC_DCHECK_EQ(data->num_frames(), kTwoBandFilterSamplesPerFrame);

        for (size_t i = 0; i < two_bands_states_.size(); ++i) {
            std::array<std::array<int16_t, kSamplesPerBand>, 2> bands16{};
            std::array<int16_t, kTwoBandFilterSamplesPerFrame> full_band16{};
            FloatS16ToS16(data->channels(0)[i], full_band16.size(), full_band16.data());
            WebRtcSpl_AnalysisQMF(full_band16.data(), data->num_frames(),
                                  bands16[0].data(), bands16[1].data(),
                                  two_bands_states_[i].analysis_state1,
                                  two_bands_states_[i].analysis_state2);
            S16ToFloatS16(bands16[0].data(), bands16[0].size(), bands->channels(0)[i]);
            S16ToFloatS16(bands16[1].data(), bands16[1].size(), bands->channels(1)[i]);
        }
    }

    void SplittingFilter::TwoBandsSynthesis(const ChannelBuffer<float> *bands,
                                            ChannelBuffer<float> *data) {
        RTC_DCHECK_LE(data->num_channels(), two_bands_states_.size());
        RTC_DCHECK_EQ(data->num_frames(), kTwoBandFilterSamplesPerFrame);
        for (size_t i = 0; i < data->num_channels(); ++i) {
            std::array<std::array<int16_t, kSamplesPerBand>, 2> bands16{};
            std::array<int16_t, kTwoBandFilterSamplesPerFrame> full_band16{};
            FloatS16ToS16(bands->channels(0)[i], bands16[0].size(), bands16[0].data());
            FloatS16ToS16(bands->channels(1)[i], bands16[1].size(), bands16[1].data());
            WebRtcSpl_SynthesisQMF(bands16[0].data(), bands16[1].data(),
                                   bands->num_frames_per_band(), full_band16.data(),
                                   two_bands_states_[i].synthesis_state1,
                                   two_bands_states_[i].synthesis_state2);
            S16ToFloatS16(full_band16.data(), full_band16.size(), data->channels(0)[i]);
        }
    }

    void SplittingFilter::ThreeBandsAnalysis(const ChannelBuffer<float> *data,
                                             ChannelBuffer<float> *bands) {
        RTC_DCHECK_EQ(three_band_filter_banks_.size(), data->num_channels());
        RTC_DCHECK_LE(data->num_channels(), three_band_filter_banks_.size());
        RTC_DCHECK_LE(data->num_channels(), bands->num_channels());
        RTC_DCHECK_EQ(data->num_frames(), ThreeBandFilterBank::kFullBandSize);
        RTC_DCHECK_EQ(bands->num_frames(), ThreeBandFilterBank::kFullBandSize);
        RTC_DCHECK_EQ(bands->num_bands(), ThreeBandFilterBank::kNumBands);
        RTC_DCHECK_EQ(bands->num_frames_per_band(),
                      ThreeBandFilterBank::kSplitBandSize);

        for (size_t i = 0; i < three_band_filter_banks_.size(); ++i) {
            three_band_filter_banks_[i].Analysis(
                    rtc::ArrayView<const float, ThreeBandFilterBank::kFullBandSize>(
                            data->channels_view()[i].data(),
                            ThreeBandFilterBank::kFullBandSize),
                    rtc::ArrayView<const rtc::ArrayView<float>,
                            ThreeBandFilterBank::kNumBands>(
                            bands->bands_view(i).data(), ThreeBandFilterBank::kNumBands));
        }
    }

    void SplittingFilter::ThreeBandsSynthesis(const ChannelBuffer<float> *bands,
                                              ChannelBuffer<float> *data) {
        RTC_DCHECK_LE(data->num_channels(), three_band_filter_banks_.size());
        RTC_DCHECK_LE(data->num_channels(), bands->num_channels());
        RTC_DCHECK_LE(data->num_channels(), three_band_filter_banks_.size());
        RTC_DCHECK_EQ(data->num_frames(), ThreeBandFilterBank::kFullBandSize);
        RTC_DCHECK_EQ(bands->num_frames(), ThreeBandFilterBank::kFullBandSize);
        RTC_DCHECK_EQ(bands->num_bands(), ThreeBandFilterBank::kNumBands);
        RTC_DCHECK_EQ(bands->num_frames_per_band(),
                      ThreeBandFilterBank::kSplitBandSize);

        for (size_t i = 0; i < data->num_channels(); ++i) {
            three_band_filter_banks_[i].Synthesis(
                    rtc::ArrayView<const rtc::ArrayView<float>,
                            ThreeBandFilterBank::kNumBands>(
                            bands->bands_view(i).data(), ThreeBandFilterBank::kNumBands),
                    rtc::ArrayView<float, ThreeBandFilterBank::kFullBandSize>(
                            data->channels_view()[i].data(),
                            ThreeBandFilterBank::kFullBandSize));
        }
    }

}  // namespace webrtc
